Regulating system



y 13, 1941- D. W.'EXNER 2,241,811

REGULATING SYSTEM Filed May 31, 1940 ly 2. I l I age a! Main Regulator Coil Vol 1 All In Regulating Resistome All Out WITNESSES: INVENTOR Patented May 13, 1941 UNITED STATES PATENT OFFICE pany, East Pittsburgh. Pa, a corpora on of ivania Pennsy Application May 31, 1940, Serial No. 338,089

Claim This invention relates to voltage regulating systems.

In voltageregulators it is desired to employ apparatus and particularly magnetic operating elements which are light in weight, low in cost and highly sensitive. Different apparatus has been developed meeting these requirements, but it has been found that the operating characteristics of such equipment are not altogether satisfactory. For example, in the simpler and lighter types of magnetic elements, such as those utilized in a commercial type of regulator, the overall pull curve with respect to position is definitely non-linear, rendering it extremely difilcult to properly match it with the calibrating spring characteristic. In such cases it has been necessary to employ compounding in proportion to load current or field current in an effort to improve the operating characteristics. Such oompounding has, however, not been entirely satisfactory since it effects a change of the entire overall pull curve.

An object of this invention is to provides regulating system for a generator including opposed windings for controlling the operation of a voltage controlling resistor in accordance with a function of the generator voltage.

Another object of this invention is to provide for regulating the output voltage L- a generator having two parallel connected field windings by utilizing a compounding winding in series with one of the field windings for cooperating with a winding responsive to the output voltage of the generator for controlling the operation of a voltage controlling resistor in accordance with the function of the generator voltage.

Other objects and advantages of this invention will be apparent from the following description when taken in conJunction with the accompanying drawing, in which:

Figure 1 is a tic view of the improved apparatus and system embodying the features of this invention; and

Fig. 2 is a graph. the curves of which illustrate the operating characteristic of a system embodying the features of this invention as compared with the operating characteristic of a similar system .which lacks one of the features of this invention.

Referring to Fig. l of the drawing. the invention is illustrated by reference to a regulating system for regulating the voltage of a generator II. The generator ll illustrated is driven by any suitable prime mover, not shown, and an armature i2 electrically connected as by conductors l4 and II to any given load which is to be supplied. In the particular embodiment illustrated, the generator III is provided with a plurality of shunt field windings l8 and 20 connected in parallel across the armature 12. In order to control the energization of the field windings i8 and 20, a resistor 22 having a plurality of resistor sections 24 -is associated with the field windings i8 and 20 and so disposed that a different portion of the resistor 22 is electrically connected in series circuit relation with each of the field windings l8 and 20.

As illustrated, the variable resistor 22 comprises one of the elements of a rheostatic controller which controls the energization of the field windings l8 and 20 in response to the output voltage of the generator III. In order to control the number of resistor sections 24 in circuit with the field windings i8 and 20, respectively, and to control the manner in which the resistor sections are included in the circuit, a control unit comprising a magnetic structure 26 and a leaf spring assembly 28 is provided and so associated with the resistor 22 and the conductors I4 and it as to effectively control the electrical connections of the resistor sections 24.

The leaf spring assembly 28 corresponds in structure to that disclosed in the copending application of C. R. Hanna, et al., Serial No. 203,876, filed April 23, 1938, for Regulators, and assigned to the same assignee as this invention. Without going into a detailed discussion of the leaf. spring assembly 28, it comprises a plurality of leaf springs 30 arranged in a stack having their fixed ends insulated from each other by layers 82 of fish paper or other suitable insulating material and connected by conductors 34 to a plurality of points or taps between the resistor sections 24 of resistor 22. The opposite ends of the leaf springs 30 carry suitable contact members I6 and are biased into engagement with a stop of any suitable insulating material. The stop It is provided with a sloping surface It for limiting the motion of the leaves in one direction and for spacing the free ends of the spring leaves 30 out of circuit closing engagement. The driving element 42 carried by a movable arm 44 actuates the leaf springs ill away from the stop when actuated, as will be explained more fully hereinafter.

In practice, the stop It is so positioned on the supporting base of the assembly and with respect to the ends of the leaf springs 30 that the springs are actuated against the sloping stopp s surface ll with a slight loading or biasing force and are accurately spaced from one another at their free ends regardless of a lack of straightness of the individual leaves 38. Although not shown in the drawing, the stop 38 is usually disposed for movement about a given point on the supporting base of the assembly to vary the angle of the sloped stopping surface 48 relative to the ends of the spring leaves 38, whereby the spacing between the leaves will be increased by a counter-clockwise movement of the stop 88 or decreased by a clockwise movement of the stop. Such an arrangement of the spring leaves 88 and the stop 38 permits a free unrestricted movement of the spring leaves 38 in a direction away from the sloping surface 48 of the stop 38.

The magnetic structure 26 employed in conjunction with the spring leaf assembly 28 for controlling the movement of the spring leaves 88 can be of any suitable arrangement, or as illustrated, the arrangement of the magnetic structure for mounting and actuating the movable arm 44 may correspond to that disclosed in a copending application of Ralph A. Geiselman, Serial No. 219,217, filed July 16, 1937, for Regulators, and assigned to the same assignee as this invention. The magnetic structure 28 diagrammatically illustrated is provided with a pivot 48 about which the movable lever arm 44 is adapted to move against the bias of a spring 48 in accordance with the force exerted on an armature 58 carried by the movable arm 44 and positioned within an air gap of the stationary core 82 of the magnetic circuit energized by winding 84. Thewinding 54 is 50 connected by conductors 88 and 58 as to be energized in accordance with the voltage across conductors I4 and I8.

As embodied in the system of this invention, the core structure 52 also carries a compounding winding 88 which is electrically connected in series with the field winding 28 and the resistor sections 24 associated with the field winding 28. This compounding winding 88 is so disposed on the core member 52 as to magnetically oppose the winding 54, so that, as will be explained more fully hereinafter, a higher voltage across conductors I4 and I6 will be required to effect the operation of the driving member 42 in con trolling the number of resistor sections connected in circuit with the field winding 28.

Although illustrated for an extreme condition of the circuit, the magnetic structure 28 and leaf spring assembly 28 are usually so arranged that for a given voltage across conductors I4 and I8 the magnetic pull on the armature 58 balances the force of the spring 48 to maintain the lever arm 44 in such a position as to permit a portion of the spring leaves 38 to be spaced apart, thereby electrically connecting a portion or a number of the resistor sections 24 in circuit with the field windings 28 and I8.

In operation, assuming that the prime mover, not shown, is operating the generator I8 at a given speed for developing a given voltage across conductors I4 and I8, the winding 84 is energized in'accordance with the voltage across the conductors I4 and I8 so as to normally ffect the separation of the spring leaves 88 beginning at the righthand side of the stack and progressing towards the left while at the same time by reason of the separation 01 the contact members 88 ating characteristic in terms of the voltage of the main regulator coil plotted against the amount of regulating resistance in the field circuit is illustrated by curve 82 and shows a decided droop from the desired voltage 83 when all of the regulating resistor is shunted from the circuit with the field windings. As is quite apparent, it is desired to so raise this curve that it approximates the desired output voltag oi the generator for all points of the curve. Thus with the prime mover initiating the actuation of the generator to deliver a predetermined voltage across conductors I4 and I8, as the voltage tends to increase to the predetermined voltage instead of securing an operation of the spring lea! assembly 28 to insert resistor sections 24 in circuit with the field winding 28 at the low output voltage indicated by the extreme right point of curve 62, the compounding winding 88 of this invention magnetically opposes the efiect of the winding 84 to permit the generator I8 to deliver a higher voltage approximating the desired output voltage as represented by curve 84 oi Fig. 2 before the magnetic pull 0! the magnetic structure 28 becomes of sufficient value to effect the operation of the resistor actuating mechanism to efiect a progressive insertion of the resistor sections 24 in series with the field winding 28.v

As is evident from the drawin with the compounding winding 88 magnetically opposing the main winding 84, the spring leaves 88 which control the insertion'of the resistor sections 24 associated with the field winding 28 are effected at a substantially higher output voltage which approximates the desired output voltage than it the compounding winding 88 is omitted from the circuit. Further, since the compounding windin 88 is connected in series circuit with the field winding 28 and the resistor sections 24 associated therewith, the strength 01' the winding for magnetically opposing the main winding 84 progressively diminishes as the resistor sections 24 are progressively inserted in series with the field winding 28. With all of the resistor sections 24 connected in circuit with the field winding 28, the compounding winding 88 has a constant strength and has no further efiect on the shape of the regulated voltage curve, as illustrated in Fig. 2, when additional resistor sections 24 associated with the field winding I8 are progressively connected in series with the field winding I8.

In operation, assuming the generator I8 is impressing a predetermined voltage on the conductors I4 and I8, and all or the resistor sections 24 are connected in series circuit relation with the field winding 28 and a portion or the resistor sections 24 are connected in series circuit relation with the field winding I8, then 11' for any reason the voltage across conductors I4 and I8 is decreased, the winding 84 is accordingly deenergized, while the winding 88 remains constant and the driving member 42 biased by the spring member 48 actuates the spring leaves 88 towards the right away from the stop 88 to progresively short circuit or shunt more 01' the resistor sections 24 from series circuit relation connections with the field winding I8. I! such shunting of the resistor sections associated with the field winding I8 is insumcient to eilect the energizetion or the winding I8 to produce the desired increase in the generator voltage, additional sections 24 of the resistor 22 which are associated with the field winding 28 are shunted, thereby so varying the energization oi the compounding of value, the winding 54 is further energized, the

winding SI remaining constant to actuate the driving member 42 from its en ment with the spring leaves It to connect the resistor sections in series with the field winding II to decrease the tion of the winding and thereby decrease the voltage delivered by the generator ill.

with the regulating system oi this invention utilizing a plurality oi shunt fields connected in parallel and the variable resistor having a diti'erent portion connected in series circuit relation with each of the field windings and the associated apparatus disposed to progressively control the number of resistor sections introduced in circuit with the respective field windings and the compounding winding associated with one oi' the field windings and its associated resistor sections, it is evident that a very sensitive control oi the volte generated is obtained. In addition to the advantages 0! the compounding coil for obtaining operation of the resistor operating mechanism at a higher voltage than would be the case it the compounding were not employed. it is evident that with the resistor sections connected in series circuit relation as described that the energization oi the field windings is secured in a predetermined sequence which, since the eiiects of the field windings on the generated voltage are cumulative, provides for good regulation 0! the generated voltage at a value which approximates the desired generated voltage throughout the operating range of the resistor regulating mechanism By providing the compounding, as described hereinbeiore, so that it affects the operation oi. only that portion of the resistor sections 24 associated with the one field winding, it is evident that improved sensitivity of the control 01' the output voltage of a generator is secured, since only the droopy end or the pull curve is so affected as to approximate a desired operating characteristic while the other end which normaliy does approximate the desired generated voltage is unaii'ected. With the regulating system 01 this invention consistent operation is secured having an overall sensitivity of approximately plus or minus 2% Although this invention has been described with reference to a particular embodiment thereof. it is,oicoursenottobelimitedthereto,except insofar as is necessitated by the prior art and the scope oi the appended claims.

I claim as my invention:

'1. In a voltage regulating system, in combination, a generator, the voltage of which is to be regulated, the generator being provided with a plurality of shunt field windings, a rheostat for controlling the voltage impressed on the shunt windings, means for actuating the rheos-tat, the rheostat actuating means comprising a compounding winding connecwd 1n serlescircuit relationwtthaiieldwindingandasecondwinding connected across the generator and disposed to oppose the magnetic field induced by the compounding winding, the compounding winding and the opposed winding thereby cooperating to control the operation of the rheostat operating means in accordance with a function oi the generator voltage.

2. In a voltage regulating system, in combination, a generator the voltage oi which is to be regulated, the generator being provided with a plurality of shunt field windings connected in parallel circuit relation, a resistor having a plurality oi resistor sections disposed to be connected in series circuit relation with the field windings respectively in a predetermined sequence for controlling the voltage impressed on the windings, means for actuating the resistor comprising a compounding winding connected in series circuit relation with one of the field windings and the resistor sections associated therewith and a second winding connected across the generator and disposed to oppose the magnetic field induced by the compounding winding, the compounding winding and the opposed winding thereby cooperating to control the operation of the resistor operating means in accordance with a function of the generator voltage.

3. In a voltage regulating system, in combination, a generator, the voltage of which is to be regulated, the generator being provided with a plurality oi shunt field windings connected in parallel circuit relation, a resistor having a plurality oi resistor sections disposed to be connected in series circuit relation with the field windings respectively in a predetermined sequence, means for progressively varying the number of the reslstor sections connected in circuit with the field windings for controlling the energizatlon of each field winding, and means for actuating the progressive varying means comprising a compounding winding connected in series circuit relation with one of the field windings and the resistor sections associated therewith and a second winding connected across the generator and disposed to oppose the magnetic field induced by the compounding winding, the compounding winding and the opposed winding thereby cooperating to control the operation of the resistor operating means in accordance with a function of the generator voltage.

4. In a voltage regulating system, in combination, a generator, the voltage of which is to be regulated, the generator being provided with two shunt field windings connected in parallel circuit relation, a variable resistor having a plurality oi resistor sections disposed to be connected in series circuit relation with the field windings respectively in a predetermined sequence, means responsive to the output voltage of the generator for progressively varying the number 01' resistor sections connected in circuit with the field windings for controlling the energization of the field windings in a predetermined sequence, and means comprising a compounding winding connected in series circuit relation with one of the field windings and the resistor sections associated therewith disposed to cooperate with the means responsive to the voltage 01' the generator whereby the progressive variation of the resistor sections throughout the range or the resistor is obtained to maintain the output voltage 01' the generator substantially at rated value.

DONALD W. EXNER. 

